Active air curtain apparatus, active air curtain system, and method of controlling the same

ABSTRACT

A high voltage battery unit for a vehicle and an underbody of the vehicle are provided. The high voltage battery unit mounted to the vehicle is installed under a center floor of the vehicle at the outdoor side. A drive shaft forming a drive device of the vehicle is installed to penetrate between battery built-in parts positioned at both sides with respect to a center tunnel to deliver the power of a powertrain mounted at the front of the vehicle to a rear wheel through the drive shaft.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority of Korean Patent Application No.10-2019-0123264 filed on Oct. 4, 2019, the entire contents of which isincorporated herein for all purposes by this reference.

BACKGROUND Field of the Disclosure

The present disclosure relates to a high voltage battery unit for avehicle and an underbody of the vehicle, and more particularly, to ahigh voltage battery unit for a vehicle is installed under a centerfloor, and a drive shaft of a vehicle to deliver power to a rear wheelvia the high voltage battery unit.

Description of the Related Art

A motorized vehicle that operates using an electric motor, such as ahybrid electric vehicle, a fuel cell vehicle, and an electric vehicle isequipped with a high voltage battery unit that provides driving power tothe electric motor. The high voltage battery unit includes a highvoltage battery installed in an enclosed internal space of a batterycase, a Battery Management System (BMS) configured to sense the voltage,current, temperature, and the like of each unit cell forming the highvoltage battery and configured to execute an operation thereof, and thelike. In general, a method for mounting the high voltage battery unit tothe vehicle largely includes a method of mounting the unit in a trunkspace, and a mounting the unit to be fixed under the center flooroutside the vehicle.

In a structure that mounts the high voltage battery unit in the trunkspace, it is difficult to provide a spare tire in the same space sincethe trunk space is reduced, and in particular, in a Sport UtilityVehicle (SUV) or a Multi Purpose Vehicle (MPV), it is difficult toimplement a full flat of a third row seat using a luggage room. In astructure of that mounts the high voltage battery unit under the centerfloor, it is difficult to deliver the power of a powertrain (engine andmotor) mounted to the front of the vehicle to the rear wheel, andtherefore, it is necessary to separately mount a rear wheel drive motorto implement All Wheel Drive (AWD), and in particular, it isdisadvantageous to the power performance because the size of the rearwheel drive motor may not be increased due to the restriction of theinstallation space.

The foregoing explained as the background is intended merely to aid inthe understanding of the background of the present disclosure, and isnot intended to mean that the present disclosure falls within thepurview of the related art that is already known to those skilled in theart.

SUMMARY

The present disclosure is a high voltage battery unit for a vehicle andan underbody of the vehicle in which a high voltage battery unit isinstalled under a center floor, and a drive shaft of a vehicle maydeliver power to a rear wheel through the high voltage battery unit. Anobject of the present disclosure is to provide a high voltage batteryunit for a vehicle and an underbody of the vehicle, which may maximizethe utilization of a trunk space, thereby being advantageous formerchantability, drive the rear wheel using the power of a powertrainwithout using a rear wheel drive motor, thereby being advantageous forthe cost and the weight, in particular, increasing the rigidity of avehicle body through the vehicle connection structure of the highvoltage battery unit, and therefore, enhancing Ride & Handling (R&H)performance and Noise Vibration Harshness (NVH) performance of thevehicle.

A high voltage battery unit for a vehicle according to the presentdisclosure for achieving the object may include a battery built-in partcoupled to both sides under a center floor of a vehicle, respectivelyand having a high voltage battery built-in therein; and a connectingportion configured to connect between the battery built-in partspositioned at both sides thereof, to form an installation space in thefront and rear direction of the vehicle, and to penetrate a drive shaftof the vehicle between the battery built-in parts of both sides thereofthrough the installation space.

Further, an underbody of a vehicle according to the present disclosuremay include a center floor constituting the lower portion of thevehicle; and a high voltage battery unit having battery built-in partscoupled to both sides under a center floor, respectively and having ahigh voltage battery built-in therein, and a connecting portionconfigured to connect between battery built-in parts, to form aninstallation space in the front and rear direction of the vehicle, andto penetrate a drive shaft of the vehicle between the battery built-inparts of both sides thereof through the installation space.

The underbody of the vehicle may further include a front cross memberpositioned at the front of the high voltage battery unit, extending inthe left and right direction of the vehicle, and coupled to the centerfloor, and the front cross member may form the load pass by connectingside sills and front cross members positioned at the left and rightsides of the vehicle. The underbody of the vehicle may include a rearcross member positioned at the back of the high voltage battery unit,extending in the left and right direction of the vehicle, and coupled tothe center floor, and the rear cross member may form the load pass bybeing connected with side sills positioned at the left and right sidesof the vehicle.

Additionally, the underbody of the vehicle may include a front crossmember and a rear cross member positioned at the front and the rear ofthe high voltage battery unit, respectively, extending in the left andright direction of the vehicle, coupled to the center floor, having bothend portions connected to side sills positioned at the left and rightsides of the vehicle, and connected with the high voltage battery unit.The outer circumference of the high voltage battery unit may besurrounded by side sills of both sides thereof and the front crossmember and the rear cross member positioned at the front and the rearthereof.

The connecting portion may be indented along a center tunnel formed onthe center floor to form the installation space in the longitudinaldirection of the vehicle, and the drive shaft may be positioned in theinstallation space to be disposed to penetrate between the batterybuilt-in parts of both sides thereof. In addition, the connectingportion may be formed to be open downward while connecting the upperportions of the battery built-in parts positioned at both sides thereof,and a space open downward from the connecting portion may become theinstallation space in which the drive shaft is positioned. Theconnecting portion may be formed to be open upward while connecting thelower portion of the battery built-in parts positioned at both sidesthereof, and a space that upward from the connecting portion may becomethe installation space in which the drive shaft is positioned.

The underbody of the vehicle may further include a traverse membercoupled to the lower surface of the battery built-in part to extend inthe left and right direction, and a first end of the traverse member maybe connected to a side sill of the vehicle to form the lateral loadpass. The underbody of the vehicle may include a longitudinal membercoupled to the lower surface of the battery built-in part to extend inthe front and rear direction, and the front end of the longitudinalmember may be connected to the front cross member and the rear end ofthe longitudinal member is connected to the rear cross member to formthe forward and backward load pass.

The underbody of the vehicle may further include a traverse membercoupled to the lower surface of the battery built-in part to extend inthe left and right direction; and a connecting portion reinforcingmember indented into the connecting portion and coupled to extend alongthe installation space. A first end of the traverse member may beconnected to a side sill of the vehicle and a second end of the traversemember may be connected to the connecting portion reinforcing member toform the lateral load pass.

The drive shaft may be mounted to at least any one among the front crossmember or the rear cross member or the high voltage battery unit. A seatcross member disposed in the left and right direction above the frontcross member and the center floor may overlap vertically with the centerfloor interposed therebetween. The front cross member may be connectedto each other through a flange with the center floor interposedtherebetween in a state disposed at the front or the rear with respectto the seat cross member in the left and right direction above thecenter floor.

Side sills positioned at the left and right sides of the vehicle mayinclude the upper surface, the lower surface, and the side surface, andthe left and right ends of the center floor may be connected to the sidesurface of the side sill and thus, the lower surface of the center floorand the side surface of the side sill may form an accommodating space.The upper portion of the battery built-in part may be accommodated inthe accommodating space, and the lower portion of the battery built-inpart is protruded downward from the side sill. The front cross memberand the rear cross member may include two side parts and a connectionpart for connecting two side parts, respectively. The outside end of theside part may be connected to the side sill to form the lateral loadpass. Both ends of the connection part may be formed with a coupledsurface to which the drive shaft is coupled, and both sides of thecoupled surface may be formed with a bead connected with the side part.

An exemplary embodiment according to the present disclosure is astructure in which the high voltage battery unit mounted to themotorized vehicle may be fixed under the center floor for the vehicle atthe outdoor side, and therefore, may maximize the utilization of thetrunk space, thereby being advantageous for the merchantability.Further, an exemplary embodiment of the present disclosure is aconfiguration of penetrating the drive shaft forming the drive device ofthe vehicle between the battery built-in parts of both sides thereofthrough the installation space in the structure of installing the highvoltage battery unit under the center floor and then deliver the powerof the powertrain to the rear wheel, and it is advantageous for thecost, the weight, and the fuel economy by not using the separate rearwheel drive motor.

Further, an exemplary embodiment according to the present disclosure isa configuration in which the high voltage battery unit installed underthe center floor may be connected with the vehicle body structure suchas the side sill, the front side member, and the rear side memberthrough the traverse member and the longitudinal member, and the frontcross member and the rear cross member, and therefore, it may bepossible to increase the rigidity of the vehicle body, thereby enhancingthe R&H performance and NVH performance of the vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of thepresent disclosure will be more clearly understood from the followingdetailed description when taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is an exploded perspective diagram of a high voltage battery unitand a drive device according to an exemplary embodiment of the presentdisclosure;

FIGS. 2 and 3 are a bottom diagram and a side diagram of the coupledstate of FIG. 1 according to an exemplary embodiment of the presentdisclosure;

FIGS. 4 and 5 are cross-sectional diagrams taken along the line I-I andthe line II-II in FIG. 2 according to an exemplary embodiment of thepresent disclosure;

FIG. 6 is an exploded perspective diagram of a front cross member and arear cross member according to an exemplary embodiment of the presentdisclosure;

FIG. 7 is a diagram illustration the coupling structure of theconnection parts into the center tunnel according to an exemplaryembodiment of the present disclosure;

FIGS. 8 and 9 are diagrams illustrating the coupling structure of afront cross member and a seat cross member for each exemplary embodimentof the present disclosure; and

FIG. 10 is a diagram of another exemplary embodiment for theinstallation space of a connecting portion in which a drive shaft isinstalled.

DETAILED DESCRIPTION

It is understood that the term “vehicle” or “vehicular” or other similarterm as used herein is inclusive of motor vehicles in general such aspassenger automobiles including sports utility vehicles (SUV), buses,trucks, various commercial vehicles, watercraft including a variety ofboats and ships, aircraft, and the like, and includes hybrid vehicles,electric vehicles, combustion, plug-in hybrid electric vehicles,hydrogen-powered vehicles and other alternative fuel vehicles (e.g.fuels derived from resources other than petroleum).

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the disclosure.As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof. As used herein, the term “and/or”includes any and all combinations of one or more of the associatedlisted items.

Unless specifically stated or obvious from context, as used herein, theterm “about” is understood as within a range of normal tolerance in theart, for example within 2 standard deviations of the mean. “About” canbe understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%,0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear fromthe context, all numerical values provided herein are modified by theterm “about.”

Hereinafter, a high voltage battery unit for a vehicle and an underbodyof a vehicle according to an exemplary embodiment of the presentdisclosure will be described with reference to the accompanyingdrawings. In a motorized vehicle that operates the vehicle using anelectric motor, a high voltage battery unit that provides driving powerto the electric motor is mounted thereon, and an exemplary embodiment ofthe present disclosure, as illustrated in FIGS. 1 to 9, includes a highvoltage battery unit 100 fixedly installed under a center floor 210 forthe vehicle, and a drive shaft 320 forming a drive device 300 of thevehicle may be configured to deliver power to a rear wheel 230 throughthe high voltage battery unit 100 in the front and rear direction of thevehicle.

The high voltage battery unit 100 may include a battery case 110 havingan enclosed internal space, a high voltage battery 120 fixedly installedin the enclosed internal space of the battery case 110, a BMS 130configured to operate the high voltage battery 120, and in particular,may be divided into battery built-in parts 140 of both sides in whichthe high voltage battery 120 has been built-in, and a connecting portion150 for connecting the battery built-in parts 140 of both sides thereof.The high voltage battery unit 100 may be fixed under the center floor210 of the vehicle at the outdoor side.

The center floor 210 may be formed with a center tunnel 211 thatprotrudes upward and extends in the front and rear direction of thevehicle, the battery built-in part 140 may be installed to be positionedat the left and right positions of the center tunnel 211, and theconnecting portion 150 for connecting the battery built-in part 140 maybe installed in the form inserted into the center tunnel 211 in a curvedshape to be protrude upward similar to the center tunnel 211.

In other words, the connecting portion 150 has a portion, whichprotrudes upward while connecting the upper portion of the batterybuilt-in part 140 positioned at both sides with respect to the centertunnel 211, indented along the center tunnel 211, the connecting portion150 extends along the longitudinal direction of the vehicle while beingformed to be open downward to form an installation space 160, and thedrive shaft 320 forming the drive device 300 may be positioned in theinstallation space 160 of the connecting portion 150 that is opendownward, to thus install the drive shaft 320 to penetrate between thebatter built-in parts 140 of both sides thereof.

The drive device 300 of the vehicle may include a powertrain 310 havingan engine and a motor, and a drive shaft 320 that delivers the power ofthe powertrain 310. The powertrain 310 may be installed to be fixed to asubframe 220 positioned at the front of the vehicle, the drive shaft 320may have a first end connected with the powertrain 310 and disposed toextend in the front and rear direction of the vehicle, and as the driveshaft 320 is disposed to be positioned in the installation space 160 ofthe connecting portion 150 of the high voltage battery unit 100, thedrive shaft 320 may be installed to penetrate between the batterybuilt-in parts 140 of both sides thereof.

The drive shaft 320 may be connected to be power-deliverable with therear wheel 230, and as the power generated in the powertrain 310 isdelivered to the rear wheel 230 through the drive shaft 320, the rearwheel 230 may be driven by the power of the powertrain 310 mounted tothe front of the vehicle. Since the high voltage battery unit 100 isinstalled to be positioned under the center floor 210, a front crossmember 400 and a rear cross member 500 may be installed to be fixedunder the center floor 210 at the front position and the rear positionof the high voltage battery unit 100, respectively.

Both the front cross member 400 and the rear cross member 500 may extendin the left and right direction of the vehicle and having both endsconnected to side sills 240 positioned at the left and right sides ofthe vehicle, and therefore, may form the load pass toward the side sill240. Further, the front cross member 400 may be connected with the rearend of a front side member 250 to form the load pass capable ofdelivering the load to the front side member 250, and the rear crossmember 500 may be configured to be connected to the front end of a rearside member 260 to form the load pass capable of delivering the load tothe rear side member 260. Since both the front cross member 400 and therear cross member 500 are connected with vehicle body structures (e.g.,the center floor, the side sill, the front side member, and the rearside member), it may be possible to increase the rigidity of the vehiclebody, thereby enhancing R&H performance and NVH performance of thevehicle.

The high voltage battery unit 100 installed to be positioned under thecenter floor 210 at the outdoor side of the vehicle may be installed asa structure that is surrounded by the side sills 240 having the outercircumference positioned at both sides thereof and the front crossmember 400 and the rear cross member 500 positioned at the front andrear thereof, and therefore, the installation position of the highvoltage battery unit 100 may be regulated by the side sills 240positioned at both sides thereof and the front cross member 400 and therear cross member 500 positioned at the front and rear thereof.Additionally, the high voltage battery unit 100 may have a structurecapable of being sufficiently protected against the impact from thefront and rear direction thereof and the left and right directionthereof.

The drive shaft 320 of the drive device 300 installed to penetrate theinstallation space 160 of the connecting portion 150 may be mounted toat least any one among the front cross member 400 or the rear crossmember 500 or the high voltage battery unit 100, and therefore, may havea strong coupling force. A seat cross member 270 may be coupled to bedisposed in the left and right direction thereof above the center floor210, and the front cross member 400 may be disposed to overlap the seatcross member 270 vertically with the center floor 210 therebetween,thereby securing more enhanced durability through the vertical overlapstructure between the seat cross member 270 and the front cross member400, thereby further strengthening the vehicle body strength and thevehicle body rigidity.

As another example, the front cross member 400 may also be a structurethat is connected to each other through flanges 271, 401 with the centerfloor 210 interposed therebetween in a state positioned at the front orthe rear with respect to the seat cross member 270. The front crossmember 400 and the rear cross member 500 may include two side parts 410,510, and connection parts 420, 520 for connecting the two side parts410, 510, respectively. The side parts 410, 510 may have the crosssections formed in a U shape while being formed in a substantiallystraight-line shape, and the connection parts 420, 520 may have thecross sections formed in a U shape similar to the side parts 410, 510while being formed in a tunnel shape, which is convex upward.

The connection parts 420, 520 may be installed in the form inserted intothe center tunnel 211 of the center floor 210. The outside ends of theside parts 410, 510 may all be connected to the side sill 240 of thevehicle to form the lateral load pass. The inside ends of the side parts410, 510 may be coupled to overlap both ends of the connection parts420, 520 to maintain a strong coupling force. Both the side parts 410,510 and the connection parts 420, 520 may have shapes with crosssections formed in a U shape to be open upward. Since the flanges 411,421, 511, 521 of the portion that is open upward are in surface contactwith the lower surface of the center floor 210, the spaces between thecenter floor 210 and the side sill 240 and between the side parts 410,510 and the connection parts 420, 520 may form an enclosed closed space280, and it may be possible to further strengthen the strength andrigidity of the vehicle body by the enclosed closed space 280.

Coupled surfaces 422, 522 to which the drive shaft 320 is coupled may beformed at both ends of the connection parts 420, 520, and beads 423, 523connected with the side parts 410, 510 may be formed at both sides ofthe coupled surfaces 422, 522. The coupled surfaces 422, 522 may beformed in a plane to strengthen the coupling force with the drive shaft320 but are not limited thereto, and may be formed in a plane of thesame shape as the mounted surface of the drive shaft 320 to be coupledin surface contact with each other. Further, the beads 423, 523 formedon the connection parts 420, 520 may be formed to be connected up to theside parts 410, 510 and may further strengthen the rigidity of thecoupled portion between the connection parts 420, 520 and the side parts410, 510 through the beads 423, 523.

First reinforcing brackets 430, 530 may be coupled to the inner surfacesof the side parts 410, 510; and the first reinforcing bracket 430coupled to the side part 410 of the front cross member 400 may becoupled with the front end of the longitudinal member 700 to bedescribed later and the second reinforcing bracket 530 coupled to theside part 510 of the rear cross member 500 may be coupled with the frontend of the longitudinal member 700 to be described later. Since thefirst reinforcing brackets 430, 530 may be coupled to the coupledportion of the front cross member 400 and the longitudinal member 700and the coupled portion of the rear cross member 500 and thelongitudinal member 700, respectively, it may be possible to furtherstrengthen the rigidity of the coupled portion. Second reinforcingbrackets 440, 540 for strengthening the rigidity of the coupled portionmay be coupled to the coupled surfaces 422, 522 to which the drive shaft320 is coupled at the connection parts 420, 520.

The lower portion of the high voltage battery unit 100 installed to bepositioned under the center floor 210 at the outdoor side of the vehiclemay be supported by a plurality of traverse members 600 and a pluralityof longitudinal members 700, and further, the high voltage battery unit100 may be connected with the vehicle body structure. In other words, inthe high voltage battery unit 100, the plurality of traverse members 600that extend in the left and right direction and are spaced apart fromeach other in the front and rear direction may be coupled to the lowersurface of the battery built-in part 140, the longitudinal member 700that extends in the front and rear direction may also be coupled to bepositioned by one for each battery built-in part 140 on the lowersurface of the battery built-in part 140. Further, the high voltagebattery unit 100 may include a connecting portion reinforcing member 800indented in the connecting portion 150 and coupled to extend in thefront and rear direction along the installation space 160.

The transverse member 600 may be installed across the longitudinalmember 700, and in this case, a first end of the transverse member 600may be connected to the side sill 240 of the vehicle and a second end ofthe transverse member 600 may be connected to the connection portionreinforcing member 800 to form the lateral load pass. Further, since thetraverse member 600 is connected with the longitudinal member 700, theforward and backward load pass may also be formed.

As another example, the transverse members 600 may be positioned at theleft and right sides of the longitudinal members 700, respectively, tobecome a structure in which first ends of the transverse members 600 maybe connected to the left and right sides of the longitudinal members700, respectively, and second ends of the transverse members 600 thatare not connected with the longitudinal members 700 may be connectedwith the side sill 240 and the connecting portion reinforcing member800. This structure may reduce the vertical height of the member as astructure of not overlapping the traverse member 600 and thelongitudinal member 700 vertically. The side sills 240 positioned at theleft and right sides of the vehicle may be configured so that thelongitudinal cross section includes an upper surface 241, a lowersurface 242, and a side surface 243, and the left and right ends of thecenter floor 210 are connected to the side surface 243, thereby formingan accommodation space 290 that is open downward by the lower surface ofthe center floor 210 and the side surface 243 of the side sill 240 underthe center floor 210.

Since the battery built-in part 140 of the high voltage battery unit 100may be installed to be positioned in the accommodation space 290, theupper portion of the battery built-in part 140 may be accommodated inthe accommodation space 290, and the lower portion of the batterybuilt-in part 140 may be installed to be protruded downward from theside sill 240. Since the center floor 210 may be lowered downward asclose as possible to the ground through the installation structure ofthe battery built-in unit 140, it may be possible to secure a sufficientindoor space, and further, as most of the upper end of the batterybuilt-in part 140 may be positioned in the accommodation space 290, itmay be possible to sufficiently space the interval between the roadsurface and the battery built-in part 140.

Meanwhile, it may also be possible to implement a structure in which theconnecting portion 150 of the high voltage battery unit 100 may beformed to be open upward while connecting the lower portion of thebattery built-in part 140 positioned at both sides thereof with respectto the center tunnel 211 as in FIG. 10, a space that is open upward andextends along the longitudinal direction of the vehicle becomes theinstallation space 160, and the drive shaft 320 forming the drive device300 may be positioned in the installation space 160 of the connectingportion 150 that is open upward to install the drive shaft 320 topenetrate between the battery built-in parts 140 of both sides thereof.

As described above, an exemplary embodiment according to the presentdisclosure is a structure in which the high voltage battery unit 100mounted to the motorized vehicle may be installed to be fixed under thecenter floor 210 of the vehicle at the outdoor side, and therefore, maymaximize the utilization of the trunk space, thereby being advantageousfor the merchantability. Further, an exemplary embodiment according tothe present disclosure is a configuration in which the drive shaft 320forming the drive device 300 of the vehicle in a structure of installingthe high voltage battery unit 100 under the center floor 210 maypenetrate between the battery built-in parts 140 of both sides thereofthrough the installation space 160 of the connecting portion 150 andthen deliver the power of the powertrain 310 to the rear wheel 230, andit is advantageous for the cost, the weight, and the fuel economy by notusing a separate rear wheel drive motor.

Additionally, an exemplary embodiment according to the presentdisclosure is a configuration in which the high voltage battery unit 100installed under the center floor 210 has been connected with the vehiclebody structure such as the side sill 240, the front side member 250, andthe rear side member 260 through the traverse member 600 and thelongitudinal member 700, the front cross member 400 and the rear crossmember 500, and the like, and therefore, it may be possible to increasethe rigidity of the vehicle body, thereby enhancing Ride & Handling(R&H) performance and Noise Vibration Harshness (NVH) performance of thevehicle.

While it has been illustrated and described with respect to the specificexemplary embodiments of the present disclosure, it will be apparent bythose skilled in the art that various improvements and changes of thepresent disclosure may be made within the technical spirit of thepresent disclosure as provided by the following claims.

What is claimed is:
 1. A high voltage battery unit for a vehicle,comprising: a battery built-in part coupled at both sides under a centerfloor of the vehicle, respectively and having a high voltage batterybuilt-in therein; and a connecting portion that connects between thebattery built-in parts positioned at both sides thereof, to form aninstallation space in the front and rear direction of the vehicle, andto penetrate a drive shaft of the vehicle between the battery built-inparts of both sides thereof through the installation space.
 2. Anunderbody of a vehicle, comprising: a center floor forming a lowerportion of a vehicle; and a high voltage battery unit including batterybuilt-in parts coupled at both sides under the center floor,respectively and having a high voltage battery built-in therein, and aconnecting portion configured to connect between battery built-in parts,to form an installation space in the front and rear direction of thevehicle, and to penetrate a drive shaft of the vehicle between thebattery built-in parts of both sides thereof through the installationspace.
 3. The underbody of the vehicle according to claim 2, furthercomprising a front cross member positioned at the front of the highvoltage battery unit, extending in the left and right direction of thevehicle, and coupled to the center floor, wherein the front cross memberforms the load pass by connecting side sills and front cross memberspositioned at the left and right sides of the vehicle.
 4. The underbodyof the vehicle according to claim 2, further comprising a rear crossmember positioned at the back of the high voltage battery unit,extending in the left and right direction of the vehicle, and coupled tothe center floor, wherein the rear cross member forms the load pass bybeing connected with side sills positioned at the left and right sidesof the vehicle.
 5. The underbody of the vehicle according to claim 2,further comprising a front cross member and a rear cross memberpositioned at the front and the rear of the high voltage battery unit,respectively, extending in the left and right direction of the vehicle,coupled to the center floor, having both end portions thereof connectedto side sills positioned at the left and right sides of the vehicle, andconnected with the high voltage battery unit, wherein the outercircumference of the high voltage battery unit is surrounded by sidesills of both sides thereof and the front cross member and the rearcross member positioned at the front and the rear thereof.
 6. Theunderbody of the vehicle according to claim 2, wherein the connectingportion is indented along a center tunnel formed on the center floor toform the installation space in the longitudinal direction of thevehicle, and wherein the drive shaft is positioned in the installationspace to be disposed to penetrate between the battery built-in parts ofboth sides thereof.
 7. The underbody of the vehicle according to claim2, wherein the connecting portion is open downward while connecting theupper portions of the battery built-in parts positioned at both sidesthereof, and wherein a space open downward from the connecting portionbecomes the installation space in which the drive shaft is positioned.8. The underbody of the vehicle according to claim 2, wherein theconnecting portion is open upward while connecting the lower portion ofthe battery built-in parts positioned at both sides thereof, and whereina space open upward from the connecting portion becomes the installationspace in which the drive shaft is positioned.
 9. The underbody of thevehicle according to claim 2, further comprising a traverse membercoupled to the lower surface of the battery built-in part to extend inthe left and right direction, wherein a first end of the traverse memberis connected to a side sill of the vehicle to form the lateral loadpass.
 10. The underbody of the vehicle according to claim 5, furthercomprising a longitudinal member coupled to the lower surface of thebattery built-in part to extend in the front and rear direction, whereinthe front end of the longitudinal member is connected to the front crossmember and the rear end of the longitudinal member is connected to therear cross member to form the forward and backward load pass.
 11. Theunderbody of the vehicle according to claim 2, further comprising: atraverse member coupled to the lower surface of the battery built-inpart to extend in the left and right direction; and a connecting portionreinforcing member indented into the connecting portion and coupled toextend along the installation space, wherein a first end of the traversemember is connected to a side sill of the vehicle and a second end ofthe traverse member is connected to the connecting portion reinforcingmember to form the lateral load pass.
 12. The underbody of the vehicleaccording to claim 5, wherein the drive shaft is mounted to at least oneof the front cross member, the rear cross member, and the high voltagebattery unit.
 13. The underbody of the vehicle according to claim 3,wherein a seat cross member disposed in the left and right directionabove the front cross member and the center floor overlaps verticallywith the center floor interposed therebetween.
 14. The underbody of thevehicle according to claim 3, wherein the front cross member isconnected through a flange with the center floor interposed therebetweenin a state disposed at the front or the rear with respect to the seatcross member in the left and right direction above the center floor. 15.The underbody of the vehicle according to claim 2, wherein side sillspositioned at the left and right sides of the vehicle include the uppersurface, the lower surface, and the side surface, wherein the left andright ends of the center floor are connected to the side surface of theside sill to form an accommodating space by the lower surface of thecenter floor and the side surface of the side sill, and wherein theupper portion of the battery built-in part is accommodated in theaccommodating space, and the lower portion of the battery built-in partprotrudes downward from the side sill.
 16. The underbody of the vehicleaccording to claim 5, wherein the front cross member and the rear crossmember include two side parts and a connection part for connecting twoside parts, respectively, and wherein the outside end of the side partis connected to the side sill to form the lateral load pass.
 17. Theunderbody of the vehicle according to claim 16, wherein both ends of theconnection part are formed with a coupled surface to which the driveshaft is coupled, and wherein both sides of the coupled surface isformed with a bead connected with the side part.